Metallizing operation



Patented Nov. 11, 1941 I 2,262,072

UNITED sTATEs "PATENT OFFICE METALLIZING ornna'non Thomas H. Vaughn, Niagara FalIs N. Y aloignor l to Union Carbide and Carbon Research Laboratories, Inc., a corporation or New York No Drawing. Application January 10, 1839,

Serial No. 250,139 r 12 Claims. (01. 91-703) m fisfi lt c lid fim ced d fi ipi mm ilif iitftfifi f w me in ,a an spray azeoro c ureo e a an voaonto the surface of an article, for example, by tile golventki t1lzmong suitable solvents, yielding means of a spray gun; and it is an object or azeo ropes the lower alkyl borates, may be the invention to provide a process of obtaining 5 mentioned alcohols, such as methanol and ethaan improved bond between the metal particles no]; ketones, such as acetone and methyl isobutyl of which the sprayed coating is composed, and ketone; and certain chlorinated solvents, such as between the metallic coating as a whole and the e chl e y n s e mp o a e tropic article to which it is applied. It is a further obmixtures containing volatile iluxes and adapted ject of the invention to decrease the discoloration l0 sirens: inntlhizhigrotcless may be mglilitioried a :nixor loss of metallic lustre of the metallic coatin o e l ore. and me ano con aincaused by the conditions under which the metal- 18 7 w t of the m 8- mixture or he spray or atomized metal is produced and protrietlaylboratefand ethanol, containing 25% by jected onto the article being coated therewith. welg t of the ormer; a mix r f t iisop opvl The difliculties indicated above have been borate and methanol, containing 32% by weight traced to the presence of a thin film of metallic of the former; and a mixture of trimethyl borate 0131165 formedflfn the Surface of the metal nargrid acetone, containing 35% by weight of tliie ti es during e spraying operation. The presormer. T 1 c es con g the albl borate n ent invention is based upon my discovery that amount substantially in excess of that present in the formation of this oxidic film can be nearly the azeotropic composition are preferable for cerquite prevented by t t 3p tain services. The presence of small amounts of operation, of volatile fluxes, and those Emme- Volatile impurities such as the of the type described in the pendlngUmted st t usual denaturants for ethyl alcohol, apparently patentoapglsigation Serial No. 250,140, filed Jan- 2 3: g i g gfheat reqmred f r th m uary1,1 ,hyA.R,. leand'LEVE-llghn. 5 cases 8 e 0 @1118 for an invention enti zd "Volatile welding Zing P9Iatin is-devehped by a gas fiamesuch fluxesy These volatile or volatmzable fluxes as an oxyacetylene flame, I find it convenient to comprise or medium bomng nqmds. the apply the volatile flux by impregnating the heat= sential ingredients of which are the alkyl esters mg gas with in the manner described in the of one id h above-mentioned patent application Serial No. igtur ac fi 8 alkyl esters of sum: wins and 250 1 0 In other cases as for example where f j 'g 5323 55 g fi gigf gmggg g the heat for melting the metal is developed by the gas or gases used in the metallizing operation is gii g g i' s g g 535g g gg g g in suihcient proportion to bring about the desired redgcm as such i hydrogen or megthaahe I g result. I attribute the beneficial action of such it fi i to mpregmte the inert gas'or the welding fluxes to their strongly reducing chem reducing gas with the volatile flux in similar cal action which inhibits oxidation of the metal manner gigrgicles, and to the dissolving action of the bol'ic Preferably the gas stream employed for atom e and/or silicon dioxide produced by the mm the molten metal and for mjectm the combustion of the volatile fl upon such m 46 g p g metallic spray upon the article to be coated there= amounts of metal oxides as me. he formed during y with is impregnated continuously and uniformly, e metamzmg operation with a selected amount of the volatile flux in Among Mame fluxes especially suitable suitable manner such as that described in the use in the process are distilled methyl, ethyl and above.mentioned cgpending application. Thus, P PY hora-ties; methyl and ethyl silicates; all or a selected portion of the gas stream so emmixtures of such horates and/or silicates; and ployed may be passed, unde a fixed uniform solutions of crude or distilled volatile borates or preur over th exposed surface of a body of silicates in volatile organic solvents. Particularly the liquid flux maintained at a suitable temperaadvantageous are mixtures of the volatile alkyl ture or the gas may he bubbled through a body borates with organic solvents which form azeo of the liquid flux of fixed depth. The gas may be tropic mixtures with the said box-eta. When dehydrated prior to contact with the flux. using such mixtures, it is preferred to employ the The method of the invention has been emcomponents in at least approximately the ratio ployed for such diverse operations as coating the in which they occur in their azeotropic oomposi= surface of a bonded altmdum mold with bronzetion. This may be accomplished by contacting and coating sand-blast steel articles with movable, mold plicated objects were reproducible with ease.

Spraying processes upon which the present in-' bronze for-the production of removable coatings, useful in the reproduction of medals, etc. Comarative tests made with and without flux showed that, in the case of mold coatings, strongly coherent casts or shells having extremely sharp margins and fine details were produced when the volatile flux was used. In the case of coated articles, the lustre of the coating, and its adherence when subjected to severe bend tests, were greatly improved when the volatile flux was used. The surfaces to be metal-coated were first provided with a thin suitable lubricant, such as Aquadag, i. e., a commercially available colloidal dispersion of graphite in an aqueous solution. when using "Aquadag," the treated surfaces are dried prior to spraying the metallic particles thereon. The metal reproductions thus made were readily redamage was minimized, and comvention is an improvement are disclosed, for example, in United States Patents Nos. 1,617,166 and 1,179,762, issued to M. U. Schoop; and in United States Patent No. 1,178,551, issued to Stolleet al.

This application is a continuation-in-part of my pending application, Serial No. 87,666, filed June 27, 1936, for improvement in Metallizing operation." v

I claim:

,1. A spray metallizing process which comprises spraying molten metal particles onto an article 'to be coated therewith by means of a jet of a gas impregnated witha volatile flux. comprising at least one ester selected from the group consisting of the alkyl esters of alkyl esters of silicic acids.

2. A spray metallizing process which comprises spraying molten metal particles onto an article to be coated therewith by means of a dry gas impregnated with a volatile flux comprising at least one ester selected from the group consisting of the alkyl esters of boric acids and the alkyl esters of silicic acids.

3. A spray metallizing process which comprises spraying molten metal particles onto an article to be coated therewith by means of a jet of a gas impregnated with a volatile flux comprising methyl borate.

4. A spray metallizing process which comprises spraying molten metal particles onto an article to be coated therewith by means of a jet of a gas impregnated with a volatile flux comprising methyl silicate.

- 5. A spray metallizing process which comprises spraying molten metal particles onto an article to be coated therewith by means of a jet of a gas impregnated with a volatile flux comprising a mixture of vapors of a volatile organic solvent and at least one ester selected from the group consisting of the alkyl esters of boric acids and the alkyl esters of silicic acids.

6. A spray metallizing process which comprises spraying molten metal particles onto an article film of graphite-or with a to be coated therewith by means of a jet of a gas impregnated with a volatile flux comprising an alkyl borate and a volatile organic solvent forming an azeotropic mixture with the said borate, said borate and solvent being present in approximately the ratio tropic mixture.

'7. In a metallizing operation wherein a metal coating is deposited on an article by spraying molten metal particles onto the article at a spraying zone by means of a jet of gas, the method of improving the bond between the metal particles and of inhibiting Surface discoloration of the deboric acids and the consisting of the posited metal, which comprises impregnating a selected portion of the said gas flowing to the spraying zone continuously and uniformly with a volatile flux comprising at least one ester selected from the group consisting of the alkyl esters of boric acids and the alkyl esters of silicic acids, and spraying molten particles onto said article by means of a jet of gas essentially comprising the resultant flux-impregnated gas mixture.

I 8. A spray metallizing impregnating an inert process which comprises gas with a volatile flux selected from the group consisting of the alkyl esters of boric acids and the alkyl esters of silicic acids, and spraying molten metal particles onto an article to be coated therewith by means of a jet of the thus-impregnated gas.

9. A spray metallizing process which comprises continuously impregnating a flowing stream of a gas with a uniform regulated amount of a volatile flux comprising an ester selected from the group alkyl esters of boric acids and the alkyl esters of silicic acids, and spraying molten metal particles onto an article to be coated therewith by means of a jet of the thusimpregnated gas.

10. A spray metallizing process which comflowing stream of a gas rate, and spraying an article to be coated therewith by means of a jet of the thus-impregnated gas.

11. A spray metallizing process which comprises spraying molten metal particles onto an article to be coated therewith of a gas containing a uniform regulated amount of a volatile alkyl borate and methyl alcohol, the said borate being present in admixture with said alcohol in an amount at least as great as that present in the azeotropic mixture of said borate and said alcohol.

- 12. A spray metallizing process which comprises spraying molten metal particles onto an article to be coated therewith by means of a jet of a gas containing a uniform regulated amount of a volatile alkyl borate and ethyl alcohol, the said borate being present in admixture with said alcohol in an amount at least as great as that present in the azeotropic mixture of said borate and said alcohol.

THOMAS H. VAUGHN.

in which they exist in their azeoby means of a jet 

